WO 03/049641 discloses a cylindrical stent with a longitudinal rotational axis and a plurality of metal stenting rings arranged at spaced intervals along the axis, and carried on an apertured cylindrical polymeric mesh. The polymeric mesh being relatively flexible, the composite stent is comparatively flexible (allowing the stent cylinder to be bendy in the sense that the long axis can easily move from straight to curved configurations) while the metal rings provide a radial strength or force that can push bodily tissue radially outwardly from the lumen of the stent, which strength or force is comparable with conventional metal stents. In this way, one can enjoy the high radial force of a metal stent in combination with the flexibility of polymers to allow the stent to bend with the surrounding bodily tissue.
However, building stents from a composite of metal and polymer requires special production techniques. In implantable prostheses, the task of joining two materials as dissimilar as metal and polymer is one that designers prefer to avoid.
The published patent art is rich in proposals to use shape memory polymers for manufacturing stents. See, for example, WO 2004/110315; WO 2005/027792; WO 03/096934; U.S. Pat. No. 4,950,258; US-A1-2003/0055198 and WO 2004/110313. However, in all of these prior proposals, there is no recognition of various inventive aspects disclosed herein.